It is well documented that maintaining a correct tire pressure improves handling, increases gas mileage, and extends the useful life of vehicle tires. Moreover, maintaining a correct tire pressure is an important consideration to the safe operation of a vehicle. Despite its irrefutable importance, tire pressure may not be monitored and maintained frequently enough by many in the driving public. Even well maintained tires may undergo a loss of pressure during the operation of a vehicle after sustaining damage, creating a potentially hazardous situation to the operator. In addition, with the advent of “extended mobility tires” (EMT) and their increasingly widespread commercial presence, it may be difficult for a vehicle operator to detect a low pressure or leak condition and take appropriate action. As a result, extended use of a tire in a low pressure condition beyond the manufacturer's recommended limit may occur.
Tire pressure monitoring systems are known and are increasingly utilized for the purpose of monitoring one or more tire parameters and alerting an operator when any of the measured parameters exceeds a preset threshold value. A timely warning encourages the driver to properly maintain tire inflation pressures. Such systems typically comprise one or more sensors that continuously measure tire parameters such as temperature and pressure and communicate measured data to a remote receiver for analysis. The purpose of a tire monitoring system is to provide the driver with a warning should an anomaly occur in one or more tires. Typically tire pressure and temperature are reported parameters. To be useful, the information must be quickly communicated and be reliable. However, displaying data derived from raw sensor measurement of temperature and pressure is not always sufficient to accurately represent the status of a tire that is undergoing a low rate of leakage. Moreover, tire monitoring systems that issue a warning only whenever a large change in tire pressure is detected are inadequate when pressure change within a tire is small and the tire pressure has been below recommended levels for a long period of time. Achieving a system and method that can issue a warning in low leakage situations or when a tire has been below recommended pressure for a long time has heretofore been problematic.
A need, therefore, continues to exist for a method of processing information in a tire undergoing a slow rate of leakage or has been below a recommended pressure for a long period of time. The desired interpretive framework should be robust, founded upon sound methodology, and providing a high degree of versatility. Various types of sensors are available for pressure detection, including piezoelectric sensors, electronic sensors, carbon sensors, optical reflection sensors, capacitive sensors, inductive sound sensors, and ultrasonic sensors. The desired interpretive methodology should be capable of utilization with and be independent of sensor, communication, and data processing hardware so as to find application in the wide range of monitoring systems in use today. Moreover, the interpretive methodology should require a relatively small amount of computer processing memory to further lower the associated hardware cost. Fundamentally, the interpretative methodology should deliver a timely warning to the driver when a tire is undergoing either a rapid deflation or a low rate of leakage but still above a minimum inflation threshold.